1. Field of the Invention
This invention relates to a retractable leg assembly, and in particular, a retractable and steerable leg assembly for use with an amphibious vehicle.
2. Description of the Related Art
Numerous attempts have been made to produce leg assemblies that are suitable for amphibious vehicles. Amphibious vehicles have a number of design challenges, the majority of which centre around the problem of translating the wheels from a deployed position to and from a retracted position.
For the amphibious vehicle to work well on the water, the wheels should be well out of the way, and the hull should retain fairly clean lines, so that drag is minimised. And yet when the vehicle is to be used on land, the tires must be of a suitable size, adequate ground clearance is required, and a method of steering is required.
These diverse requirements have often lead to designs which use significant amounts of space within the vehicle to stow the wheels, and/or have complex systems with doors and seals through which the wheels pass, and when steering is also incorporated, complex methods to engage with some sort of steering system are employed.
Another limitation of previous designs is an inability of the vehicles to retract or extend their wheels when on dry ground, for example to beach the vehicle, or to raise it off the ground again.
This complexity, sometimes coupled with poor use of space, has prevented most of the previous designs from ever becoming a commercial success. Complexity will not only drive costs higher, but also becomes a maintenance burden that is aggravated by operations in salt or fresh water. A simplified solution is required, having the minimum of moving parts, and the least interruption to the watertight structure of the hull of the vehicle, producing the least possible drag when the vehicle is operating on water, using the minimum of space within the hull of the vehicle, and in addition having sufficient power to extend the wheels to raise the vehicle off the ground when required to.